2 ounces prosciutto, sliced 1/4 inch thick and cut into 1/4-inch dice
1 1/2 cups orzo or other small pasta, such as tubettini, ditalini or acine di pepe
3 1/2 cups water
Salt and freshly ground pepper
1/2 cup grated Parmigiano-Reggiano cheese
Heat 3 tablespoons of the olive oil in a large, deep skillet. Add the mushrooms and leeks and cook over moderately high heat, stirring occasionally, until the vegetables are softened and lightly browned, about 8 minutes. Using a slotted spoon, transfer the vegetables to a bowl.
Add the remaining 1 tablespoon of olive oil and the prosciutto to the skillet and cook over moderately high heat, stirring, until the prosciutto is lightly browned, about 3 minutes. Add the pasta and cook for 3 minutes longer. Stir in the mushrooms and leeks.
Add the water to the skillet, season the pasta with salt and pepper and bring to a boil. Cover and cook over low heat until the pasta is al dente and the liquid has been absorbed, about 15 minutes. Stir in the cheese and serve.